We report the synthesis of both n-type Mg2Si and p-type MnSi1.73 using reaction sintering employing spark plasma sintering (SPS) process. The thermoelectric device was fabricated using these synthesized thermoelectric materials having a ZT value of ~ 0.7 for n-type Mg2Si and ~ 0.55 for p-type MnSi1.73. The two design combination of unicouple thermoelectric devices were fabricated; nickel contacts at hot & cold ends in first device and graphite contact at hot end & nickel contact at cold end in another device. The device comprised of n-type Mg2Si & p-type MnSi1.73 legs each with dimensions of 4 × 4 × 10 mm. The voltage and current output characteristics of this thermoelectric device were evaluated at temperature gradient between hot and cold ends in the range of 50 to 350 K. The maximum open circuit voltage output (~135mV) and maximum current output (~200 mA) from nickel contacts device were obtained at ?T ≈350 K, which would be much higher at elevated operating temperatures and employing several such thermoelectric couples.